It's a nuisance to have to type two commands to compile a new version of
[our example]. Although it's certainly easy to make a shell file that does
the job, there's a better way, one that will generalize nicely later on
when there is more than one source file in the program. ...

make is most useful when the program being created is large enough to be
spread over several source files, but it's handy even for something as
small as [our example].

In other words, one advantage that make provides is a simple interface for
building any program, whether small or large. Said interface should not
come at the cost of complexity, but good makefiles are simple anyway (the
one in their example is two lines).